Method and apparatus for stabilizing the trajectory of a reaction-propelled missile

ABSTRACT

In a method and apparatus for stabilizing the trajectory of a reaction-propelled missile, tensile forces are exerted at the stern of the missle through a single tensile member connected to the stern, the tensile forces, at angles of incidence of the missile differing from zero, producing moments which rotate the missile back about its center of gravity. The single tensile member, at its connection with the missile, is wound on a coil at the stern of the missile, and this coil has an axis of rotation coinciding with the longitudinal axis of the missile. The single tensile member may be the cable for transmitting guiding signals to the missile, although the tensile member may be independent of this cable.

United States Patent [191 Karpa et al.

[451 Aug. 21, 1973 [75] Inventors: Giinther Karpa, Ottobrunn; Helmut Schmidt, Munich, both of Germany [73] Assignee: Messerschmitt-Bolkow-Blohm Gesellschait mit beschrankter Haftung, Munich, Germany [22] Filed: Oct. 6, 1970 [21] Appl. No.: 78,447

[30] Foreign Application Priority Data Oct. 9, 1969 Germany P 19 50 930.9

[52] US. Cl 244/3.l2, 89/1.8, 89/1.806 [51] Int. Cl F42b 15/04, F42b 13/56, F41g 7/02 [58] Field of Search 244/312; 114/21 R;

[56] References Cited UNITED STATES PATENTS 2,801,571 8/1957 Lusser 89/l.806

8/1966 Simpson ..244/3.l2 12/1964 Schindler 244/312 Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Thomas H. Webb Attorney-McGlew and Toren [57] ABSTRACT In a method and apparatus for stabilizing the trajectory of a reaction-propelled missile, tensile forces are exerted at the stern of the missle through a single tensile member connected to the stem, the tensile forces, at angles of incidence of the missile differing from zero, producing moments which rotate the missile back about its center of gravity. The single tensile member, at its connection with the missile, is wound on a coil at the stern of the missile, and this coil has an axis of rotation coinciding with the longitudinal axis of the missile. The single tensile member may be the cable for transmitting guiding signals to the missile, although the tensile member may be independent of this cable.

4 Claims, 2 Drawing Figures Patented Aug. 21, 1973 INVENTORS Gunther Kurpa Helmut Schmidt y MgWM/W ATTORNEYS METHOD AND APPARATUS FOR STABILIZING THE TRAJECTORY OF A REACTlON-PROPELLED MISSILE BACKGROUND OF THE INVENTION In a known arrangement, tensile forces, stabilizing a missle in the launching stage in the desired flight direction, are applied by a mechanical rope connection including four ropes wound on a drum. These drums run over four deflecting rollers, mounted at respective ends of a cross anchored on the ground, to the four arms of a cross secured to the stern of the missile which is to be launched vertically. As the missile is launched, the ropes unwind from the drum in such a way that the respective unwound lengths increase by equal amounts. Due to the ropes always remaining taut, the axial position of the missile, and thus also the thrust and acceleration direction, are determined. After the missile has attained a flight distance of approximately 50 meters, a velocity insuring a stable trajectory is attained and the arms, with their ropes, are cast off from the missile; for reference, see Yearbook I959 of WGL, page 328 Veronique.

SUMMARY OF THE INVENTION This invention relates to a method and apparatus for stabilizing the trajectory of a reaction-propelled missile by tensile forces exerted at the stern of the missile and, more particularly, to a simplified stabilization method which is applicable to reaction-propelled missiles whether launched horizontally or launched vertically.

In the case of horizontally launched missiles, in particular if the missiles are launched from so-called launching tubes including a gas generator producing a gas pressure accelerating the missile, relatively large movements of the missile, leaving the launching tube, in the pitch and yaw planes about the center of gravity of the missile are observable. This leads to undesired ground contacts of the missile immediately after leaving the launching tube and, when semi-automatically guided missiles are concerned, to the missile diverging outside the pick-up range of its locating device.

The objective of the present invention is to provide a remedy for this problem by simple means which have no adverse effect either on the missile or on its launching system. Proceeding from the known stabilizing method for vertically launched missiles, this objective is attained, for horizontally launched missiles, in that the rope or tensile forces stabilizing the missile are supplied by means of a single tensile member whose tensile force produces, at angles of incidence of the missile other than zero, moments which rotate the missile back about its center of gravity.

The tensile forces thus produced act as restoring moments on the missile if the latter, due to launching disorders on leaving the launching tube, undergoes accelerations about its center of gravity in the pitch plane, the yaw plane, or both. That is, the tensile forces rotate the missile back into the desired original flight direction or orientation, and thereby reduce the occurring angle of incidence oscillations in the pitch or yaw planes. The restoring moments are sign-independent when either the missile rotates about its longitudinal axis or the tensile member is coiled concentrically with the longitudinal axis of the missile, or when the tensile member is secured centrally at the stern of the missile.

Another advantage of the invention method is that the effects, which are undesirable precisely during the first flight phase, of different thrust vectors at equal immersion depth and/or duration of a jet spoiler extending into the engine jet, and due to different combustion chamber pressures, can be compensated by means of these tensile forces. For this purpose, the tensile forces are so to be rated that the undesirably large control moments are reduced to the desired value by the restoring moments produced by the tensile forces. If a missile rotating about its longitudinal axis is concerned, corotating disturbing moments, due to construction inaccuracies, also are diminished with respect to their undesired effects.

In accordance with a further characteristic of the invention, the tensile force is so selected, as to duration and magnitude, as a function of the frequency and amplitude of the undamped angle of incidence oscillations of the missile, that the generation of the desired restoring moment is completed in the maximum of an antinode of the-angle of incidence oscillation in order to remove the oscillation energy from the system.

In a preferred form of apparatus embodying the invention, a tensile member, such as a rope, for producing the tensile forces is coiled concentrically with the longitudinal axis of the missile. Preferably, this tensile member may be the cable serving to transmit guiding signals to the missile. If so, this guide signal transmitting cable is reinforced at its beginning end and cemented more firmly in its first turns than in the following turns. Alternatively, a rope brake may be provided on the missile in operative assocation with the cable uncoiling from the missile, and this brake can be disconnected as a function of the time elasping since launching. Preferably an additional tensile member should then be connected with the cable, to transmit the forces to be supplied between the rope brake and the missile.

In order to compensate, by means of a single pulling or tensile member, both the initially mentioned launch deviations and the undesired thrust vector variations at equal depths of immersion of the jet rudder, the tensile member, in accordance with a further feature of the invention, is glued in two steps, thus differing from the normal gluing of the tensile member.

An object of the invention is to provide an improved and simplified stabilization method or a reactionpropelled missile.

Another object of the invention is to provide improved and simplified apparatus for stabilizing a reaction-propelled missile.

A further object of the invention is to provide such a method and apparatus which are applicable not only to vertically launched missiles but also to horizontally launched missiles.

Another object of the invention is to provide such a method and apparatus which have no adverse effect on either the missile or its launching system.

For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a diagrammatic representation of a missile leaving its launching device and equipped with the apparatus of the invention; and

FIG. 2 is a diagram of trajectories lying in the pitch plane and differently influenced by launch deviations, plotted against time, without a tensile force being exerted at the stern of the missile and with a tensile force being exerted at the stern of the missile.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, a reaction-propelled missile l is connected, through a cable 2 wound on a coil 7, which latter is not shown in detail but is mounted in the missile, with a guiding station 4 on the ground 3. Station 4 has a launching tube 5 from which the missile is launched, for example by means of a gas generator (not shown) arranged in the launching tube 5. Cable 2 serves to transmit guiding signals to the missile, these guiding signals being generated in the guiding station 4 as a function of the off-position of the missile from the target covering straight line, as automatically perceived by a locating device 6. Approximately the first 30 meters of cable 2 are glued more firmly on the coil 7, which is arranged coaxial with the longitudinal axle of the missile, then the remaining turns. Also, this portion of cable 2 is made stronger (thicker) than the rest of the cable, to be able to transmit the required tensile forces.

Instead of this firm gluing of cable 2, a rope brake may be provided and arranged to be disconnectable, for example through a delay circuit, to produce the increased initial traction. For this purpose, cable 2 is provided with an additional tensile element to be able to supply the required forces without damage to cable 2.

The disturbances occurring on leaving the launching tube cause, in the pitch plane shown in FIG. 1, as well as in the yaw plane (not shown), a positive or negative angle of incidence a of the missile about its center of gravity S due to the interference moment 8,. In proportion to this angle of incidence, air forces are produced which cause trajectories F differing from the desired trajectory F. The maximum permissible limits of these deviating trajectories F are given by the ground clearance and the pick-up range A of locating device 6.

The intensified cable traction on the missile, which acts on the center of gravity S through the lever arm a, produces a restoring moment M about center of gravity S, so that the trajectory of the missile strays much less than is shown by the curves F in FIG. 2. The tensile force to be applied by the tensile member or cable must be selected, as to duration and magnitude, as a function of the frequency and amplitude of the undamped angle of incidence oscillations of the missiles, making certain that the production of the desired restoring moment is completed in the maximum of an antinode of the angle of incidence oscillation. For missiles with dual engines, for example missiles with an acceleration engine and a cruising engine in one combustion chamber, an undesired different transverse thrust, at equal immersion depth and immersion time, is produced when using jet rudders, due to the different combustion chamber pressures in the two burning phases. Until the present invention, the necessary compensation has been obtained by a correction of the guiding commands, namely the changed immersion times or by flow-mechanical means, as, for example, changed immersion depths or correcting jet rudders. By adaptation of the intensified cable traction to the variation in time of the combustion chamber pressure, a constant control efficiency with respect to time can be obtained.

For the purpose of solving both problems with a single tensile element, such as a cable, the tensile element is glued in two steps, differing from the normal gluing.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. In a method of stabilizing the trajectory ofa rocket having a cable wound in a coil mounted at the stern of the rocket and having an end connected to a ground station for unwinding of the cable as the rocket is launched: the improvement comprising connecting said cable as a single tensile member between the stern of the rocket and a fixed ground point; launching the rocket; and creating and maintaining, through the single tensile member, tensile forces, at angles of incidence of the rocket differing from zero for a predetermined initial portion of the rocket trajectory to minimize rocket deviation from an optimum trajectory and produce restoring moments as required, for rotating the rocket about its center of gravity.

2. In a method of stabilizing the trajectory of a rocket, the improvement claimed in claim 1, including an initial step of orienting said coil so that its axis is concentric with the longitudinal axis of the rocket prior to rocket launching.

3. In apparatus for stabilizing the trajectory of a rocket by tensile forces exerted at the stern of the rocket, the improvement comprising a tensile force exerting member which is wound in a coil which is concentric with the longitudinal axis of the rocket and mounted at the stern of the rocket; said tensile force exerting member being a cable the coil convolutions of which are glued to each other, with the first several convolutions of the coil, immediately adjacent the free end of the cable, being more firmly glued together than the subsequent convolutions.

4. In a rocket of the character incorporating a coiled cable disposed at the aft end thereof for payout during rocket flight, said cable being adapted for connection to a fixed ground point, the step of securing the initial convolutions of the coil to be paid off to a greater degree than the balance of the coil convolutions; attaching and fixing the free end of the cable to a fixed ground point; launching the rocket; and creating and maintaining, through the cable, tensile forces, at angles of incidence of the rocket differing from zero for a predetermined initial portion of the rocket trajectory to minimize rocket deviations from an optimum trajectory and produce restoring moments as required, for rotating the rocket about its center of gravity.

I0! i t i 

1. In a method of stabilizing the trajectory of a rocket having a cable wound in a coil mounted at the stern of the rocket and having an end connected to a ground station for unwinding of the cable as the rocket is launched: the improvement comprising connecting said cable as a single tensile member between the stern of the rocket and a fixed ground point; launching the rocket; and creating and maintaining, through the single tensile member, tensile forces, at angles of incidence of the rocket differing from zero for a predetermined initial portion of the rocket trajectory to minimize rocket deviation from an optimum trajectory and produce restoring moments as required, for rotating the rocket about its center of gravity.
 2. In a method of stabilizing the trajectory of a rocket, the improvement claimed in claim 1, including an initial step of orienting said coil so that its axis is concentric with the longitudinal axis of the rocket prior to rocket launching.
 3. In apparatus for stabilizing the trajectory of a rocket by tensile forces exerted at the stern of the rocket, the improvement comprising a tensile force exerting member which is wound in a coil which is concentric with the longitudinal axis of the rocket and mounted at the stern of the rocket; said tensile force exerting member being a cable the coil convolutions of which are glued to each other, with the first several convolutions of the coil, immediately adjacent the free end of the cable, being more firmly glued together than the subsequent convolutions.
 4. In a rocket of the character incorporating a coiled cable disposed at the aft end thereof for payout during rocket flight, said cable being adapted for connection to a fixed ground point, the step of securing the initial convolutions of the coil to be paid off to a greater degree than the balance of the coil convolutions; attaching and fixing the free end of the cable to a fixed ground point; launching the rocket; and creating and maintaining, through the cable, tensile forces, at angles of incidence of the rocket differing from zero for a predetermined initial portion of the rocket trajectory to minimize rocket deviations from an optimum trajectory and produce restoring moments as required, for rotating the rocket about its center of gravity. 